I like plain tomato sauce. There is this place in Buffalo NY, called "Chef's Restaurant," around since 1929. It has the most amazing tomato sauce.
Oddly enough, "plain" tomato sauce (which sounds - and is - a deceptively simple dish) is one of those things that can be surprisingly hard to get just right.
For one thing, it needs heat, and for another, it needs time.
Fresh tomatoes - unless they come from a country where the sun kisses them with the blessing of heat - can be flavourless.
In fact, imported tomatoes are usually pretty devoid of flavour; yes, for a few weeks in summer - when there is a glut - and you grow your own, or have access to someone who does just that - they can be full of flavour.
Anyway, when using fresh tomatoes, with a view to rendering them into a tomato sauce, I find that sautéing them is not quite enough; I tend to roast them first, in order to concentrate the flavour. Again, this alchemy needs both time (at least 40 minutes in a hot oven) and heat.
Re good quality canned/tinned tomatoes, (such as San Marzano tomatoes), they, too, will need both time and heat, but, this time, a low heat, as they will be on the stove top for at least 30-40 minutes.